This invention relates to pipelines and their associated support systems and more particularly systems utilizing temperature control of the soil or fill material surrounding the support system.
Maintaining the integrity of pipelines laid above or within soil or fill is often dependent upon the fluctuations within the soil or fill. Apart from cataclysmic disturbances such as earthquakes and floods, fill or soil fluctuations are caused by soil temperature changes. Temperature of the soil and more importantly periodic temperature variations caused by the change of seasons affect the support characteristics of the soil or fill. Expansion and contraction occurs as well as changes in moisture content. Variations are amplified in non-stable soil types, namely permafrost which is prevalent in northern regions such as Alaska.
Although it can be difficult to prevent or protect against cataclysmic events, it is possible to maintain the temperature of soil or fill material supporting a pipeline within a range where the soil or fill material is stabilized, typically in a frozen condition. What is desired is a simple and efficient way to stabilize soil or fill material beneath a pipe or pipeline.
The present invention overcomes disadvantages in existing support systems by providing a system which stabilizes the soil or fill material surrounding a pipeline support. The invention provides in one aspect a system for supporting pipe within soil or fill material which minimizes positional disturbances of the pipe despite seasonal fluctuations in atmospheric temperature. The system includes a length of double walled pipe including an inner pipe and an outer pipe, a support member which supports said double walled pipe and is placed in soil or fill material, and a wicking device which transfers energy between the inner pipe and the support member. Thus, energy is further transferred between the support member and the soil or fill material adjacent the support member to stabilize the soil or fill material.
The invention provides in another aspect a system including a length of double walled pipe including an inner pipe and an outer pipe, a support member which supports the double walled pipe and is placed in soil or fill material, a pipe stem extending from the outer pipe, and a wicking device which transfers energy between said inner pipe and said support, through the pipe stem. This variation is useful in instances where the support member is positionally offset from the point in the double walled pipe where energy is transferred from the inner pipe to the outer pipe.
The system provides an efficient method of supporting vacuum-insulated cryogenic piping installed in permafrost or other soils that have low bearing load properties. The consistency of the soil, when frozen, can sustain the load required to support the piping. A cryogenic material within the innermost pipe provides the necessary refrigeration to freeze the permafrost, or other soil, around the support structure. The invention is an improvement over existing support systems in that the most unpredictable variable in the system, soil condition, is stabilized by cooling or freezing. The superior wicking design within the system of the invention allows the system to be sized to provide just the right amount of refrigeration necessary to freeze the soil or fill material without wasting excess energy and increasing amount of refrigeration needed. These and other aspects of the invention are herein described in particularized detail with reference to the accompanying Figures.